1. Field of the Invention
The present invention relates generally to minimally invasive and less invasive surgical access. More particularly, the present invention provides retractors for soft tissues, as well as delivery devices and methods for using the retractors to provide surgical access into body cavities.
Coronary artery disease remains the leading cause of morbidity and mortality in western societies. Coronary artery disease is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow resulting in the discomfort and risks of angina and ischemia. In severe cases, acute blockage of coronary blood flow can result in myocardial infarction, leading to immediate death or damage to the myocardial tissue.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to treat the symptoms with pharmaceuticals and lifestyle modification to lessen the underlying causes of disease. In more severe cases, the coronary blockage can often be treated endovascularly using techniques such as balloon angioplasty, atherectomy, or stents.
In cases where pharmaceutical treatment and/or endovascular approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft procedure using open surgical techniques. Such techniques require that the patient's sternum be opened and the chest be spread apart to provide access to the heart. A source of arterial blood is then connected to a coronary artery downstream from an occlusion, while the patient's heart is maintained under cardioplegia and circulation is supported by cardiopulmonary bypass. The source of blood may be a vessel taken from elsewhere in the body such as a saphenous vein or radial artery, or an artery in the chest or abdomen such as the left or right internal mammary artery or the gastroepiploic artery. The target coronary artery can be the left anterior descending artery, right coronary artery, circumflex artery, or any other coronary artery which might be narrowed or occluded.
While very effective in many cases, the use of open surgery to perform coronary artery bypass grafting is highly traumatic to the patient. The procedure requires immediate post-operative care in an intensive care unit, a total period of hospitalization of seven to ten days, and a recovery period that can be as long as six to eight weeks.
Recently, it has been proposed to utilize minimally invasive surgical techniques and procedures to perform coronary artery bypass grafting and other traditionally open-chest cardiac surgical procedures. A wide variety of laparoscopic, arthroscopic, endovascular, and other minimally invasive surgical therapies have been developed. These procedures generally utilize trocars, cannulas, catheters, or other tubular sheaths to provide an artificial lumen, through which specialized tools are inserted and manipulated by the surgeon.
An exemplary minimally invasive bypass method is described in U.S. Pat. No. 5,452,733, assigned to the assignee of the present application, the full disclosure of which is herein incorporated by reference. This exemplary coronary artery bypass method relies on viewing the cardiac region through a thoracoscope and endovascularly portioning the patient's arterial system at a location within the ascending aorta. The bypass procedure is performed under cardiopulmonary bypass and cardioplegia, while the coronary anastomoses are formed within the chest cavity through the use of a plurality of trocar sheaths placed between the patient's ribs.
Although thoracoscopic methods hold great promise for decreasing morbidity and mortality, cost, and recovery time when compared to conventional open surgical coronary bypass procedures, these methods could benefit from still further improvements. In particular, the surgical access provided by known trocar sheaths has not been optimally adapted for performing thoracoscopic coronary artery bypass. The length of conventional trocar sheaths and the small size of their lumens limits the maneuverability of surgical instruments and inhibits the ability to look directly into the chest cavity while an instrument is positioned through the trocar sheath.
It would therefore be desirable to provide improved surgical access devices and methods for their use in performing less invasive coronary artery bypass grafting and other thoracoscopic surgical procedures, and minimally invasive surgical procedures in general. It would be particularly desirable if such devices and techniques provided atraumatic retraction of soft tissue of the chest wall to create the largest possible surgical access window without resorting to a sternotomy or gross retraction or removal of the ribs. Preferably, such improved surgical access devices and methods would provide a flexible access lumen which could be positioned and sized to meet the individual patient's physiology. The devices should have minimum height so as to extend as little as possible from the inner or outer surfaces of the chest wall. It would further be desirable if such access devices and methods allowed direct or magnified viewing of the internal procedure from outside the patient body, thereby decreasing the time and trauma associated with the internal surgical procedure, and increasing overall efficacy over both open surgical procedures and minimally invasive surgical procedures performed through the small trocar sheaths which have been relied on in the prior art.
2. Description of Background Art
Conventional thoracoscopic techniques are described in Landreneau et al. (1992) Ann. Thorac. Surg. 54:800-807. Conventional open surgical procedures for performing coronary artery bypass grafting are described in Kirkland and Barratt Boyes, Cardiac Surgery, John Wiley and Sons, Inc., New York, 1993 (2nd Ed.).
A minimally invasive method for performing coronary artery bypass grafting using an anterior mediastinotomy, including excision of either the third or fourth costal cartilage, is described by Robinson et al. in J. Card. Surg. (1995) 10:529-536.
U.S. Pat. No. 5,391,156 describes a flexible endoscopic surgical port having a tubular body, the outer end of which is optionally divisible into a plurality of flaps, thereby matching the length of the tubular body with the thickness of a body wall. A retainer ring engages the flaps to hold the port axially, while the hoop strength of the tubular body holds the adjacent tissue in a retracted position. U.S. Pat. No. 4,274,398 describes a surgical retractor having elastic tubes which hold hooks under radial tension from a notched frame. U.S. Pat. Nos. 4,430,991 and 4,434,791 describe similar surgical retractor frames for use with hooked members. Such a system is commercially available under the trade name LoneStar Retractor System.TM..
A surgical drape having a central open ring for insertion over known surgical retractors is commercially available from Becton Dickinson of Franklin Lakes, N.J. under the tradename Vidrape.RTM.. Relevant minimally invasive methods and devices for heart surgery are described in U.S. Pat. No. 5,452,733, U.S. Pat. No. 5,571,215, U.S. Pat. No. 5,501,698, U.S. Pat. No. 5,588,949, and U.S. patent application Ser. No. 08/486,941, filed Jun. 7, 1995, which corresponds to PCT Application No. WO 96/40354 published Dec. 19, 1996, the full disclosures of which patents and application are incorporated herein by reference.